[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.384426] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.939201] random: sshd: uninitialized urandom read (32 bytes read) [ 20.175324] random: sshd: uninitialized urandom read (32 bytes read) [ 21.142467] random: sshd: uninitialized urandom read (32 bytes read) [ 21.279116] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.17' (ECDSA) to the list of known hosts. [ 26.695366] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.896901] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.905199] IP: [] l2tp_session_free+0x11c/0x200 [ 26.911641] PGD 1bbec3067 [ 26.914285] PUD 1bbede067 PMD 0 [ 26.917783] [ 26.919414] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.923887] Dumping ftrace buffer: [ 26.927403] (ftrace buffer empty) [ 26.931098] Modules linked in: [ 26.934405] CPU: 1 PID: 3805 Comm: syz-executor368 Not tainted 4.9.113-g47bbcd6 #10 [ 26.942174] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.951510] task: ffff8801b72be000 task.stack: ffff8801b5ee0000 [ 26.957541] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.966412] RSP: 0018:ffff8801b5ee7ca0 EFLAGS: 00010246 [ 26.971843] RAX: dffffc0000000000 RBX: ffff8801cb301680 RCX: 0000000000000000 [ 26.979097] RDX: 1ffff10036bbc0d0 RSI: ffffffff836bcce1 RDI: ffff8801b5de0680 [ 26.986362] RBP: ffff8801b5ee7cc0 R08: ffff8801b72be8e8 R09: 0000000000000000 [ 26.993631] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5de0500 [ 27.000881] R13: ffff8801cb301688 R14: 0000000000000000 R15: ffffffff83013be0 [ 27.008150] FS: 0000000000b2d880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.016360] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.022224] CR2: 0000000000000080 CR3: 00000001b77c5000 CR4: 00000000001606f0 [ 27.029482] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.036737] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.043998] Stack: [ 27.046128] ffff8801d95d1980 ffff8801cb301680 ffff8801d95d1d50 ffff8801d95d1c58 [ 27.054142] ffff8801b5ee7ce8 ffffffff836c45f2 ffff8801d95d1dc0 ffff8801d95d1980 [ 27.062128] ffffffff836c4520 ffff8801b5ee7d20 ffffffff83021095 ffff8801d95d1dc0 [ 27.070125] Call Trace: [ 27.072702] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.079357] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.085657] [] __sk_destruct+0x55/0x590 [ 27.091261] [] ? sock_release+0x1c0/0x1c0 [ 27.097039] [] sk_destruct+0x63/0x80 [ 27.102383] [] __sk_free+0x4f/0x220 [ 27.107654] [] sk_free+0x2b/0x40 [ 27.112671] [] pppol2tp_release+0x239/0x2e0 [ 27.118639] [] sock_release+0x96/0x1c0 [ 27.124153] [] sock_close+0x16/0x20 [ 27.129409] [] __fput+0x263/0x700 [ 27.134490] [] ____fput+0x15/0x20 [ 27.139578] [] task_work_run+0x10c/0x180 [ 27.145272] [] exit_to_usermode_loop+0xfc/0x120 [ 27.151588] [] do_syscall_64+0x364/0x490 [ 27.157291] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.164193] Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 41 ff 8e 80 00 00 00 74 69 e8 55 1d ca fd 4c 89 ea 48 b8 00 [ 27.191326] RIP [] l2tp_session_free+0x11c/0x200 [ 27.197839] RSP [ 27.201439] CR2: 0000000000000080 [ 27.205069] ---[ end trace 9d055365fd898425 ]--- [ 27.211083] Kernel panic - not syncing: Fatal exception [ 27.216876] Dumping ftrace buffer: [ 27.220411] (ftrace buffer empty) [ 27.224097] Kernel Offset: disabled [ 27.227785] Rebooting in 86400 seconds..